Syrups, elixirs, solutions, and suspensions are traditional dosage forms for oral medication. These liquid formulations are typically measured by pouring into a spoon, but this approach has the great drawback of spillage. The risk of spillage can cause people to underfill or spill from the spoon, leading to inaccurate dosage. With elderly people, children, and the infirm, lack of motor skills or poor attention can cause difficulty in filling a spoon with a liquid and bringing it to the mouth. This can result in a serious impediment to administering the medicine. Solid formulations such as pills, tablets, and capsules are also difficult for children and for elderly, infirm people to swallow.
Recently, pharmaceutical preparations that are resistant to spilling for the oral delivery of pharmaceutically active agents have been described in the commonly owned U.S. Pat. Nos. 5,881,926, 6,071,523, 6,102,254, 6,355,258, 6,399,079, and 6,656,482 incorporated herein in their entirety by reference. U.S. Pat. Nos. 5,881,926 and 6,102,254 describe a pharmaceutical delivery system for spill resistant formulations. U.S. Pat. Nos. 6,071,523, 6,355,258, 6,399,079 and 6,656,482 describe the spill resistant pharmaceutical compositions in terms of their physico-chemical properties and methods of preparing and using those formulations. These patents describe oral dosage forms for the delivery of active agents that do not spill easily, are organoleptically pleasing and are storage stable.
The previously described spill-resistant pharmaceutical formulation for oral administration are from a squeezable container comprising a per-unit dose effective amount of a pharmaceutical agent in a suitable vehicle comprising a liquid base and a thickening or viscosity agent. In the previously described spill resistant formulations, the thickening or viscosity agent utilized most frequently was carbomer, a synthetic, high molecular weight, polymer of acrylic acid cross-linked with allylsucrose. The viscosity of the carbomer gels are known to be pH dependent. Carbomer gels exhibit maximum viscosity at about neutral pH, where the viscosity plateaus between pH values of 6.3 to 7.0. This pH-viscosity interaction of the carbomer polymer has restricted the use of weak acids and weak bases in spill resistant pharmaceutical formulations. At higher or lower pH ranges, the ranges where the weak acids and bases are most soluble, the formulations lose their spill resistant properties. Now, using clays, we have expanded the pH range available for spill resistant formulations. This enables the development of spill resistant formulations where the pharmaceutical active agents have either acidic or basic pKa's.